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Q 5. How to test the replacement of the microwave high voltage power transformer?
The RX1 gear is used to measure the cold resistance of the transformer. The secondary winding is usually a few ohms; if it is too small, there may be inter turn short circuit. The two side high voltage winding is from ten to hundreds of ohms. If it is infinite, it will be cut off; if it is small, the partial short circuit between the turns will be close; the filament winding will be close to o ohm. Mega ohmmeter (500V insulation resistance meter) or multimeter RX10 1000 ohm gear are used to measure the resistance of the primary and secondary sides to the outer shell of the transformer is larger than two megaohms. If any resistance is too small, it means that the transformer is creepage, and the insulation is bad. When measuring, we should pay attention to removing the insulating paint film on the tested parts of the transformer shell, so as to ensure the contact between the pen and the shell is good. At the same time, do not touch hands with the pen and contact with the measuring point of the conductive parts, otherwise the needle may indicate a smaller resistance. We should pay attention to this when we use multimeter to measure high-voltage capacitors and high voltage diodes.

thin film resistor
When detecting the transformer, the lead should be disconnected and retested (for example, one end of the high voltage winding will be grounded with the core and chassis), otherwise it will be misjudged. In addition, the high voltage capacitor connected to the winding should be discharged before the test to avoid electric shock.
The main common faults of the high voltage transformer are as follows.
(1) the winding or lead line is broken and the contact is bad. This makes the microwave oven unheated or unstable. First check the lead and plug in the case, if the broken line, as long as the re welding or connection is reliable, if the contact is bad, should clear the dirt, and strengthen the contact fastness of the two. (2) Partial short circuit inside the high voltage winding, leakage or short circuit between the windings and the housing. This will cause the microwave oven to not work, fuse or work unstable. First roasting or rewinding, if it can not be solved after baking, or it can not be rewound, it needs to be replaced.

This article is from ALLICDATA ELECTRONICS　LIMITED.